condition mean min max ZT0-3 2.8195533333333334 2.375575 3.051265 ZT4-7 3.22575 3.22575 3.22575 ZT8-11 2.68635 2.68635 2.68635 ZT12-15 2.70243 2.455755 2.9491050000000003 ZT16-19 2.519345 2.519345 2.519345 ZT20-23 2.974005 2.974005 2.974005